DESCRIPTION: This application aims to develop an artificial vestibular contro system based on galvanic stimulation. The investigators intend to use electrical stimulation of the inner ear with galvanic currents to induce postural movement. Recording of postural sway will be accomplished using a force plate and a motion analysis system. A moveable balance platform will be used to produce time varying aperiodic postural sway in each subject. The nov concept in the application is that galvanic stimulation could be matched to postural sway such that overall postural movements might be reduced through involuntary, external stimulation of the vestibular system without head movement.